docs: def cli(env, identifier, columns):
      """Reserved Capacity Group details. Will show which guests are assigned to a reservation."""
  
      manager = CapacityManager(env.client)
      mask = """mask[instances[id,createDate,guestId,billingItem[id, description, recurringFee, category[name]],
                guest[modifyDate,id, primaryBackendIpAddress, primaryIpAddress,domain, hostname]]]"""
      result = manager.get_object(identifier, mask)
  
      try:
          flavor = result['instances'][0]['billingItem']['description']
      except KeyError:
          flavor = "Pending Approval..."
  
      table = formatting.Table(columns.columns, title="%s - %s" % (result.get('name'), flavor))
      # RCI = Reserved Capacity Instance
      for rci in result['instances']:
          guest = rci.get('guest', None)
          if guest is not None:
              table.add_row([value or formatting.blank() for value in columns.row(guest)])
          else:
              table.add_row(['-' for value in columns.columns])
      env.fout(table)